Could you add some details? Do you think the mac doing the sharing has the problem (and the message)? Have you tried another mac to connect in? If not - what software is the VNC client?
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bmike♦Jul 26 '11 at 14:10

basic plus MobileMe back to my mac for locating the mac over the internet

basic plus Screens app from edovia to locate the mac over the internet

I haven't seen a good Apple writeup of the Lion changes - but when you log in with your OS account rather than with the VNC password - you get a distinct loginwindow process for that account whether or not that user is shown as logged in locally. This change could be causing you grief.

Put another way - screen sharing and log in is now a virtual concept - you are no longer limited to one mac log in session or tied tightly to the physical screen. User A can be using the mac and User B logs in remotely and gets their own workspace rather than seeing what A is doing or forcing A to log off.

I found that Screen Sharing was working, but I couldn't see the window showing the remote machine. I could only figure that out by being in the same room with the remote machine. :)

When I changed the display quality setting, choosing "Full Quality", then choosing "Adaptive Quality" again, Screen Sharing resized the window showing the remote machine, then I could see it. I don't know whether the old window was 0x0 size or off-screen.

I had a problem with connecting from my Lion MacBook to my SL iMac. It turned out that I needed to go into Sharing under System Preferences on the iMac, toggle off "Screen Sharing" and toggle on "Remote Management." Then they started connecting again.